GOV.UK dashboard updates

- Add ability to create 100% graphs this can be set as a stagecraft option it will
  - change the graph to use percent on the y-axis
  - change the stack render to use an equivalent of 'expand' stack option in d3
  - change the line labels to have percent as the prominent display and absolute value as secondary. To do this I merged the display methods for the two places this is displayed into one helper method
- Fixed some markup on the carers dashboards configs which had heading tags where they weren't needed
- Moved the dashboard from `dashboard` to `gov-uk`
- Moved the css for legend colour spans outside of the `figure` as they are needed in the description above the graph which isn't in the `figure`